Serum Steroid Levels Following a Large Intravenous Dose of a Steroid Sulfate Precursor During the Second Trimester of Human Pregnancy. II. Pregnenolone Sulfate

Abstract

Serum levels of pregnenolone sulfate (δ5P-S), pregnenolone (δ5P), 17α-hydroxypreg-nenolone (17δ5P), progesterone (P), 17α-hydroxy-progesterone (17P), estradiol-17β (E2) and estriol (E3)were measured by radioimmunoassay after intravenous infusion of a large dose of unlabeled δ5P-S to 9 healthy women during midtrimester pregnancy. Subjects were divided into three groups. The first group consisted of 4 subjects with a live fetus and intact placenta. The second group consisted of 3 subjects with a dead fetus and intact placenta in whom the δ5P-S infusion was performed after hypertonic saline amnioinfusion. The third group consisted of 2 subjects in whom the δ5P-S infusion was performed following passage of the fetus and placenta. δ5P-S levels fell exponentially following infusion in all subjects. The mean half-life for all subjects with an intact placenta regardless of fetal viability was 2.22 ± 0.70 hr. With removal of the fetus and placenta, the mean δ5P-S half life remained at 2.22 hr. δ5P levels increased following δ5P-S infusion from 2- to 11-fold in all subjects with an intact placenta. Removal of the placenta markedly blunted but did not completely eliminate the post infusion rise of δ5P. 17δ5P levels were highly erratic both before and after δ5P-S infusion with no distinctive pattern between groups of patients. P levels rose 1.6- to 3-fold in all subjects with an intact placenta. Removal of the placenta was associated with a fall in P levels to <5 ng/ml both before and after δ5P-S infusion. 17P levels showed no consistent change following δ5P-S infusion in any of the three groups of subjects. E2 levels fell following δ5P-S infusion to at least 50% baseline in all subjects with an intact placenta. In addition, those subjects with an intact placenta where the fetus was dead showed an even sharper fall to at least 30% baseline. With removal of the placenta, E2 levels were undetectable both before and after the δ5P-S infusion. E3 levels did not rise or fall consistently following δ5P-S infusion to subjects with a live fetus and intact placenta. Death of the fetus or removal of the fetus and placenta were associated with undetectable E3 levels both before and after the infusion of δ5P-S.